The present invention relates to an ink-jet recorder that forms an image on a recording medium by ejecting ink from nozzles provided on a recording head.
A recorder using an ink-jet method, which ejects ink on a recording medium such as recording paper to form an image thereon, is known as one of output devices of an information processing unit such as a computer or a workstation. This ink-jet recorder usually comprises recording heads on each of which ink-ejecting nozzles are provided, a carriage on which the recording heads are mounted and that moves back and forth in a predetermined direction, and a recording medium conveyer that conveys a recording medium in a direction (recording medium conveyance direction) at a right angle to the predetermined direction.
When forming an image on recording paper, the recording paper being conveyed by the recording medium conveyer is temporarily stopped and, while moving back and forth the carriage in the predetermined direction, ink is ejected from the nozzles based on the image signals including image information to form a band of image in the image-forming area, which is opposed to the nozzle exits (ink ejecting outlets), on the recording paper. After that, the recording paper is fed one band and then stopped and, while moving back and forth the carriage again in the predetermined direction, ink is ejected from the nozzles based on the image signals to form another band of image in the image forming area on the recording paper. By repeating such an operation, the whole image is formed on the recording paper.
Because ink (recording liquid) is ejected directly from the recording heads for recording on such an ink-jet recorder, the recording heads must be maintained in the state so that ink may be ejected at any time. This requires a variety of special operations that are not required for other types of recorders.
When gases, or bubbles, are mixed into a supply path, through which ink is supplied to the nozzles that are ink outlets, or into an ink reservoir (common liquid chamber) near the nozzles and when those bubbles become so large that they prevent ink from being supplied to the nozzles, ink is not ejected properly. To solve this problem, the ink and bubbles present in the area leading to, and included in, the common liquid chamber, are sucked and removed by applying a negative pressure to the nozzle surface. This operation is called suction. As will be described below, the sucking operation is also performed, with the caps removed from the heads, to remove ink accumulated in the caps by a preliminary ejection. (The suction described in the present invention is the latter suction).
Physical matters (paper powder, ink, etc.), which are adhered to the nozzle arrangement surface (face side) and prevent ink ejection, sometimes prevent ink from being ejected properly. To remove those physical matters, a flexible blade member such as a rubber blade member is used to wipe the face side. This operation is called a wiping operation. Means for performing the wiping operation is called a wiper.
Not all nozzles are used to eject ink during image formation. Therefore, ink on the nozzles from which ink is not ejected dries and those nozzles sometimes prevent link from being ejected. An operation that ejects ink to a part other than recording paper at an interval of predetermined time to prevent ink from being dried for ensuring good-quality images is a preliminary ejection. This operation is also called a xe2x80x9cpre-ejectionxe2x80x9d.
An operation that covers the face side with a cap during non-printing time to prevent ink in the nozzles from being dried is called a capping operation. Absorptive matters soaked to some degree with sucked ink are included in the cap to prevent drying.
It should be noted that pre-ejection during printing is generally executed little by little under time control and therefore a small amount of ink is accumulated in a cap over a relatively long time period. In addition, even if the operation is performed to suck accumulated ink when there is not an enough ink region in the absorptive matter in the cap, air is sucked and therefore residual ink remains in the cap. For this reason, the viscosity of ink in the cap or in the suction pump increases (viscosity increase) and, as a result, the ink adheres to the cap, to the suction pump, and to the ink path through which ink flows to the waste ink tank.
Some of the ink adhered to the suction pump or the ink flow path is re-dissolved by the sucking operation and is sent to the waste ink tank. However, there could be a possibility that the adhered ink eventually blocks the flow path, causes a pump failure, or causes the ink ejected in the cap to overflow. This problem is most noticeable when pigmented ink, which is highly water-resistant, is used because it is difficult to re-dissolve.
In view of the foregoing, it is an object of the present invention to provide an ink-jet recorder and its restoring system cleaning method that prevent ink adhesion from occurring in the restoring system and that perform the sucking operation and the pre-ejection operation smoothly.
A method for cleaning a restoring system according to the present invention is a method for cleaning a restoring system of an ink-jet recorder that ejects ink droplets from nozzles on a recording head to record on recording paper, comprising the steps of counting an accumulated number of times ink is preliminarily ejected from the nozzles on the recording head into a cap where waste ink is stored; when executing a sucking operation at a predetermined time to suck ink that has been ejected into the cap, successively ejecting ink into the cap a number of times equal to a difference between a predetermined count value and the accumulated number of times; and executing the sucking operation to suck ink stored in the cap.
An ink-jet recorder according to the present invention comprises a recording head for ejecting ink droplets from nozzles for recording on recording paper; a cap for preventing the nozzles from being dried; preliminary ejection means for bringing, at non-print time, the ink-jet recording head to a position opposed to the cap to eject the ink droplets from the nozzles to prevent bad printing; ink suction means connected to the cap for sucking ink stored in the cap; counting means for counting a number of times ink is ejected from the nozzles to the cap; and control means for successively ejecting ink into the cap a number of times equal to a difference between a predetermined count value and an accumulated count of times when executing the sucking operation at a predetermined time to suck ink that has been ejected into the cap and then executing the sucking operation to suck ink stored in the cap.
The method and the recorder according to the present invention as described above let some amount of ink flow into the ink flow paths at least before printing or at the end of printing, with no major reconfiguration of a conventional restoring knit, to prevent ink from adhering to the components of the restoring system.
In another aspect, a method for cleaning a restoring system according to the present invention is a method for cleaning a restoring system of an ink-jet recorder that ejects ink droplets from nozzles on a recording head to record on recording paper, wherein a sucking operation to suck waste ink from a cap is executed, after printing, until ink is discharged from an ink flow path provided in a downstream of the cap and wherein the sucking operation is executed, immediately before or during printing, to such an extent that ink is discharged from the cap but remains in the ink flow path.
This allows ink, which was put out before printing, to remain in the flow paths, dissolves ink adhered to the ink flow paths during printing, and lets the dissolved ink flow at the end of printing, thus solving the problem of adhered ink generated during long-time storage. As a result, the sucking operation and the preliminary ejection operation may be performed smoothly for a long time and good-quality images are ensured.
In still another aspect, a method for cleaning a restoring system according to the present invention is a method for cleaning a restoring system of an ink-jet recorder that ejects ink droplets from nozzles on a recording head to record on recording paper, wherein, when an ink preliminary ejection operation is executed at a predetermined time, a first preliminary ejection operation, which is an operation for preventing nozzles from being dried, and a second preliminary ejection operation, which is an operation for ejecting ink more times than a count value of the first preliminary ejection operation, are switched or alternately performed at a predetermined interval.
Another ink-jet recorder according to the present invention comprises a recording head for ejecting ink droplets from nozzles for recording on recording paper; a cap for preventing the nozzles from being dried; preliminary ejection means for bringing, at non-print time, the ink-jet recording head to a position opposed to the cap to eject the ink droplets from the nozzles to prevent bad printing; ink suction means connected to the cap for sucking ink stored in the cap; judging means for judging predetermined judgment data based on a predetermined criterion, the judgment data being collected, in advance, for the judgment; and control means for switching a first print operation and a second print operation for execution based on a judgment result of the judging means, the first print operation involving a first preliminary ejection operation that preliminarily ejects a predetermined amount of ink at least before starting printing or after printing, the second print operation involving a second preliminary ejection operation that preliminarily ejects more ink than the predetermined amount at least before starting printing or after printing.
As described above, switching the first print operation and the second print operation, which differ in the amount of preliminarily ejected ink, based on a predetermined criterion allows some amount of ink to be regularly supplied to the ink flow paths at least before printing and at the end of printing. This prevents ink from adhering to the restoring system components.
Switching at the predetermined interval is performed when the number of accumulated dots printed during printing reaches a predetermined number of dots, when the number of printed pages printed during printing reaches a predetermined number of forms, or when the print time used for printing reaches a predetermined time.